Preventive Maintenance Checklist for Heavy-Duty Diesel Trucks
Running a heavy-duty diesel truck fleet is all about keeping things moving—safely, efficiently, and consistently. At Doug Andrus, we know firsthand how critical preventive maintenance is to the success of any operation. Skipping scheduled checks might save a little time in the short term, but it almost always leads to costly downtime, expensive repairs, and missed delivery windows down the road. That’s why we take a proactive approach to maintenance across our fleet. It’s not just about fixing problems—it’s about preventing them.
Keeping Diesel Trucks Road-Ready with Preventive Care
Preventive maintenance isn’t just a best practice—it’s a vital part of protecting your investment. Heavy-duty diesel trucks endure long miles, harsh weather, and tough loads. Every part of the vehicle, from the engine to the electrical system, experiences wear over time. Without regular checks and timely repairs, small issues can snowball into major problems.
Our maintenance protocols at Doug Andrus are designed to:
Reduce unexpected breakdowns
Lower operating and repair costs
Improve fuel efficiency
Extend vehicle lifespan
Ensure compliance with safety and emissions regulations
Protect drivers and cargo
Whether your truck is hauling refrigerated freight, dry van freight, or heavy loads using our flatbed freight services, preventive maintenance keeps it rolling reliably.
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What Should Be on a Preventive Maintenance Checklist?
There’s no one-size-fits-all approach to preventive maintenance, but certain components should always be inspected and serviced on a routine basis. Here's what we prioritize in our inspections:
Engine Oil and Filters
Oil is the lifeblood of any diesel engine. Regular oil changes keep the engine lubricated and prevent wear and overheating. Along with the oil, we check and replace filters—including the oil filter, fuel filter, and air filter—to maintain smooth engine function.
We don't just check levels. We look at oil color, debris presence, and any signs of leaks. These small details often reveal bigger issues before they cause damage.
Transmission and Driveline
A well-functioning transmission is critical for long hauls. We inspect fluid levels, check for leaks, and monitor for delayed shifting or unusual sounds. Driveline components like U-joints and differentials are also examined for signs of wear.
Even a small vibration can indicate a driveline imbalance that, if ignored, could lead to transmission failure.
Brake System
Brake performance is non-negotiable. We inspect pads, drums, rotors, and fluid systems. Our techs also test air brake systems for pressure consistency and leaks. Brake issues escalate quickly and often show up as uneven wear or longer stopping distances.
Prompt replacement of worn brake pads is an easy win for safety and cost savings.
Don’t ignore the warning signs—stay ahead of repairs with our breakdown of Common Signs of Mechanical Issues in Heavy-Duty Diesel Trucks.
Tires and Wheels
Tires take a beating on the road. During every inspection, we look for signs of uneven wear, punctures, low tread depth, and improper inflation. We also examine wheel alignment and balance, which can greatly affect ride quality and fuel economy.
Underinflated tires wear out faster and reduce fuel efficiency. That’s why this check is one of the first things we do.
Cooling System
Diesel engines run hot. To prevent overheating, we inspect radiator levels, hoses, and connections. We also test the thermostat and water pump function. Coolant flushes are scheduled to remove sediment that can block heat transfer.
Spotting cracks or bulges in a hose before it fails is a simple way we avoid roadside breakdowns.
Electrical System and Battery
We rely heavily on electronic systems to support everything from engine diagnostics to lighting. We check battery terminals, charge levels, alternator output, and wiring integrity. A weak battery can leave a driver stranded or put strain on other systems.
Especially in colder months, staying ahead of battery issues is key.
Suspension and Steering
We inspect shocks, struts, bushings, and power steering fluid levels. If a driver reports odd noises or rough handling, we dive deeper into alignment and wear patterns. Suspension issues not only affect comfort—they impact control and braking.
This area gets special attention in our commercial truck repairs, especially for trucks covering long distances or uneven terrain.
Learn how even minor dents can lead to major risks on the road by reading How Body Damage Impacts Commercial Truck Safety and Performance.
Exhaust and Emissions Systems
Modern diesel engines must meet strict emissions standards. We monitor Diesel Particulate Filters (DPFs), Exhaust Gas Recirculation (EGR) valves, and Selective Catalytic Reduction (SCR) systems to make sure they’re functioning correctly.
These systems keep your fleet compliant and avoid fines—but they also need regular care to prevent power loss or warning lights.
Lights, Wipers, and Safety Systems
Visibility and signaling are fundamental for highway safety. We inspect all lights—headlights, brake lights, turn signals—and replace any that are dim or out. We also test windshield wipers and washer systems, especially heading into stormy seasons.
Our checklist also includes onboard safety systems, like backup alarms and collision sensors.
Building a Service Schedule That Works
Every truck has different needs based on usage, mileage, and routes. That’s why we tailor our service schedules to match each vehicle’s workload. Some systems need attention every few thousand miles, while others are reviewed quarterly or seasonally.
Here’s how we keep it structured:
Daily Pre-Trip Checks: Performed by drivers and logged.
Weekly Inspections: Light mechanical checks like fluid levels and tire pressures.
Monthly Service: Oil changes, filter replacements, and basic diagnostics.
Quarterly Maintenance: In-depth inspection of drivetrain, brakes, and cooling systems.
Annual Compliance Checks: Emissions, DOT inspections, and full diagnostic testing.
By spacing out the work and prioritizing key systems, we keep trucks running without disrupting delivery schedules.
The Doug Andrus Advantage
We take a proactive, data-driven approach to preventive maintenance. Every vehicle in our fleet is tracked, logged, and monitored to ensure timely service and top performance. Our in-house technicians are trained to catch problems early, and our support team works directly with drivers to address concerns before they escalate.
We also support independent contractors and carrier partnerships by offering expert inspections and repair services. Whether you're a longtime operator or new to the road, our maintenance programs provide peace of mind.
For those looking to invest in quality, we offer equipment for sale that's been cared for with the same precision. When we say a truck has been well-maintained, we mean it.
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Let Us Keep Your Trucks Running Strong
If you're managing a fleet or driving long haul, preventive maintenance should be non-negotiable. At Doug Andrus, we do more than just check off boxes. We build a full-circle maintenance strategy that improves safety, extends vehicle life, and boosts performance.
Contact us today to schedule service or request a custom maintenance plan. Our team is here to help you protect your equipment, your drivers, and your bottom line.
Related Questions
How often should I perform preventive maintenance on a diesel truck?
It depends on the truck’s usage, but generally every 10,000 to 25,000 miles for major components, with more frequent checks in between.
What are the benefits of a maintenance checklist?
It ensures that no critical systems are overlooked, improves safety, extends truck life, and helps avoid unexpected downtime.
Can preventive maintenance reduce fuel costs?
Yes. Well-maintained trucks run more efficiently, which leads to better fuel economy and lower operating costs over time.
What happens if I skip regular maintenance?
Skipping maintenance often results in breakdowns, expensive repairs, and lost revenue due to downtime or failed inspections.